KR20190141083A - Reflective mask blank, reflective mask, and method of manufacturing reflective mask blank - Google Patents

Abstract

The present invention relates to a reflective mask blank which can suppress defects a surface of an absorber layer by oxidizing the surface of the absorber layer, to a reflective mask blank (10A) comprising: a reflective layer (12) which reflects EUV light on a substrate (11); and an absorption layer (14) which absorbs the EUV light in the order from a substrate side, wherein the absorption layer (14) contains Sn and has a prevention layer (15) which prevents the oxidation of the absorption layer (14) on the absorption layer (14).

Description

Method for manufacturing reflective mask blanks, reflective masks and reflective mask blanks {REFLECTIVE MASK BLANK, REFLECTIVE MASK, AND METHOD OF MANUFACTURING REFLECTIVE MASK BLANK}

The present invention relates to a method of manufacturing a reflective mask blank, a reflective mask and a reflective mask blank.

In recent years, with the miniaturization of integrated circuits constituting semiconductor devices, an extreme method is used to replace conventional exposure techniques using visible light, ultraviolet light (wavelengths 193 to 365 nm), ArF excimer laser light (wavelength 193 nm), and the like. External light (hereinafter, referred to as "EUV") lithography is under consideration.

In EUV lithography, shorter wavelength EUV light is used as the light source used for exposure than ArF excimer laser light. In addition, EUV light means the light of the wavelength of a soft X-ray region or a vacuum ultraviolet region, and is specifically, the light whose wavelength is about 0.2-100 nm. As EUV light, EUV light whose wavelength is about 13.5 nm is used, for example.

Since EUV light is easily absorbed by all the substances, the refractive optical system used in the conventional exposure technique cannot be used. Therefore, in EUV lithography, reflective optical systems such as reflective masks and mirrors are used. In EUV lithography, a reflective mask can be used as the transfer mask.

In the reflective mask, a reflective layer for reflecting EUV light is formed on the substrate, and an absorption layer for absorbing EUV light is formed on the reflective layer in a pattern shape. The reflective mask is obtained by laminating a reflective layer and an absorbing layer on the substrate in this order from the substrate side, using a reflective mask blank as a disc, removing a part of the absorbing layer to form a predetermined pattern, and then washing with a cleaning liquid. Lose.

EUV light incident on the reflective mask is absorbed by the absorbing layer and reflected by the reflecting layer. The reflected EUV light is imaged on the surface of an exposure material (a wafer coated with a resist) by an optical system. As a result, the pattern of the absorbing layer is transferred to the surface of the exposure material.

In EUV lithography, EUV light is normally incident on a reflective mask from a direction inclined at about 6 ° and is reflected at an angle as well. Therefore, if the film thickness of the absorbing layer is thick, there is a possibility that the optical path of the EUV light is blocked (shadowed). If a portion of the absorbing layer that becomes the shadow due to the shadowing occurs, the pattern of the reflective mask is not faithfully transferred onto the surface of the exposure material, and the pattern accuracy may deteriorate. On the other hand, when the thickness of the absorbing layer is reduced, the light shielding performance of EUV light in the reflective mask is lowered and the reflectance of EUV light is increased, which may lower the contrast between the pattern portion of the reflective mask and other portions.

Therefore, the reflection mask blank which suppresses the fall of contrast, while faithfully transferring the pattern of a reflection mask is examined. For example, Patent Document 1 contains 50 atomic% (at%) or more of an absorber film containing Ta as a main component, and further includes Te, Sb, Pt, I, Bi, Ir, Os, W, Re, Sn, In A reflective mask blank composed of a material containing at least one element selected from among Po, Fe, Au, Hg, Ga and Al is described.

However, in the reflective mask blank described in Patent Literature 1, the surface of the absorber film is oxidized, fine particles are generated on the surface of the absorber film, and defects may occur on the surface of the absorber film. For example, when the absorber film is formed of an alloy of Ta and Sn, there is a possibility that the surface of the absorber film is oxidized and fine particles of tin oxide are generated on the surface of the absorber film. When producing a reflective mask, if microparticles exist in the place where the absorber film should be cut by dry etching, there is a possibility that this portion is not etched and becomes a pattern defect in which the absorber film remains. In this case, since the pattern defect on a reflective mask is transferred to the exposure material (resist) apply | coated to the wafer at the time of wafer exposure, it is unpreferable.

Japanese Patent Publication No. 2007-273678

An object of one embodiment of the present invention is to provide a reflective mask blank capable of suppressing oxidation of the surface of the absorbent layer and generation of defects on the surface of the absorbent layer.

One aspect of the reflective mask blank according to the present invention is a reflective mask blank having, on the substrate, a reflective layer for reflecting EUV light and an absorbing layer for absorbing EUV light in this order from the substrate side, wherein the absorbing layer is Sn. It contains, and has the prevention layer which prevents oxidation of an absorption layer on the said absorption layer.

According to one embodiment of the present invention, it is possible to provide a reflective mask blank capable of suppressing oxidation of the surface of the absorber layer and generation of defects on the surface of the absorber layer.

1 is a schematic cross-sectional view of a reflective mask blank according to the first embodiment.
2 is a flowchart illustrating an example of a method of manufacturing a reflective mask blank.
3 is a schematic cross-sectional view showing an example of another form of the reflective mask blank.
4 is a schematic cross-sectional view showing an example of another form of the reflective mask blank.
5 is a schematic cross-sectional view showing an example of the configuration of a reflective mask.
It is a figure explaining the manufacturing process of a reflective mask.
7 is a schematic cross-sectional view of the reflective mask blank according to the second embodiment.
8 is a schematic cross-sectional view showing an example of another form of the reflective mask blank.
9 is a schematic cross-sectional view of the reflective mask blank of Comparative Example 1. FIG.
It is a figure which shows the observation result of the surface of the absorption layer of the reflective mask blank of the comparative example 1. FIG.
It is a figure which shows the observation result of the surface of the absorption layer of the reflective mask blank of Example 1. FIG.
It is a figure which shows the observation result of the surface of the absorption layer of the reflective mask blank of Example 2. FIG.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail. In addition, in order to make understanding of description easy, the same code | symbol is attached | subjected about the same component in each figure, and the overlapping description is abbreviate | omitted. In addition, the scale of each member in drawing may differ from an actual thing. In the present specification, a three-dimensional rectangular coordinate system in three axis directions (X-axis direction, Y-axis direction, Z-axis direction) is used, and the coordinates on the main surface of the substrate are the X-axis direction and the Y-axis direction, and the height direction ( Thickness direction) to the Z-axis direction. The direction from the bottom of the substrate upwards (the direction from the main surface of the substrate toward the reflective layer) is made into the + Z axis direction, and the opposite direction is made the -Z axis direction. In the following description, the + Z axis direction may be referred to as up, and the -Z axis direction may be referred to as down. "-" Which shows a numerical range in this specification means including the numerical value described before and after that as a lower limit and an upper limit, unless there is particular notice.

<Reflective Mask Blanks>

The reflective mask blank according to the first embodiment will be described. 1 is a schematic cross-sectional view of a reflective mask blank according to the first embodiment. As shown in FIG. 1, the reflective mask blank 10A is formed by stacking the reflective layer 12, the protective layer 13, the absorbing layer 14, and the barrier layer 15 in this order on the substrate 11. have.

(Board)

It is preferable that the substrate 11 has a small coefficient of thermal expansion. The smaller the coefficient of thermal expansion of the substrate 11 can suppress the occurrence of deformation in the pattern formed in the absorbing layer 14 due to heat during exposure by EUV light. Specifically, the thermal expansion coefficient of the substrate 11 is preferably 0 ± 1.0 × 10 ⁻⁷ / ° C. at 20 ° C., more preferably 0 ± 0.3 × 10 ⁻⁷ / ° C.

As a small thermal expansion coefficient material, for example, it can be used, such as SiO ₂ -TiO ₂ type glass. SiO ₂ -TiO ₂ type glass, it is preferred to use quartz glass containing 90% by mass to 95% by mass of SiO _2, 5% by mass to 10% by weight of TiO _2. When the content of TiO ₂ is 5% by mass to 10% by mass, the coefficient of linear expansion in the vicinity of room temperature is approximately zero, and the dimensional change in the vicinity of room temperature hardly occurs. Further, SiO ₂ -TiO ₂ type glass is, may include a small amount of components other than SiO ₂ and TiO _2.

It is preferable that the 1st main surface 11a of the side in which the reflective layer 12 of the board | substrate 11 is laminated | stacked has high smoothness. The smoothness of the 1st main surface 11a can be evaluated with the surface roughness obtained by measuring with an atomic force microscope. As for the surface roughness of the 1st main surface 11a, the root mean square roughness Rq is 0.15 nm or less.

It is preferable that the 1st main surface 11a is surface-processed so that it may become predetermined flatness. This is for the reflective mask to obtain high pattern transfer accuracy and position accuracy. The substrate 11 preferably has a flatness of 100 nm or less, more preferably 50 nm or less, and even more preferably in a predetermined region (for example, a region of 132 mm x 132 mm) of the first main surface 11a. 30 nm or less.

In addition, it is preferable that the substrate 11 is resistant to a cleaning liquid used for cleaning the reflective mask blank, the reflective mask blank after pattern formation, or the reflective mask.

In addition, the substrate 11 preferably has high rigidity in order to prevent deformation due to film stress of the film (reflective layer 12 or the like) formed on the substrate 11. For example, the substrate 11 preferably has a high Young's modulus of 65 GPa or more.

The size, thickness, and the like of the substrate 11 are appropriately determined according to the design value of the reflective mask and the like.

The 1st main surface 11a of the board | substrate 11 is formed in rectangular or circular shape by planar view. In the present specification, the rectangle includes a mold in which rounding is formed at the corners of the rectangle and the square, in addition to the rectangle and the square.

(Reflective layer)

The reflective layer 12 has a high reflectance with respect to EUV light. Specifically, when EUV light is incident on the surface of the reflective layer 12 at an incident angle of 6 °, the maximum value of the reflectance of EUV light in the vicinity of the wavelength of 13.5 nm is preferably 60% or more, and more preferably 65% or more. Moreover, also when the protective layer 13 and the absorption layer 14 are laminated | stacked on the reflective layer 12, similarly, the maximum value of the reflectance of EUV light of wavelength 13.5 nm vicinity is preferably 60% or more, and 65% or more More preferred.

The reflective layer 12 is a multi-layered film in which a plurality of layers each of which has an element having different refractive indices as a main component is periodically stacked. In general, the reflective layer 12 is a multilayer reflective film obtained by alternately stacking a high refractive index layer having a high refractive index with respect to EUV light and a low refractive index layer having a low refractive index with respect to EUV light alternately from the substrate 11 side.

The multilayer reflective film may be laminated in multiple cycles using a single stacked structure in which the high refractive index layer and the low refractive index layer are stacked in this order from the substrate 11 side, and the laminated structure in which the low refractive index layer and the high refractive index layer are laminated in this order. You may laminate | stack multiple cycle by making it into 1 cycle. In this case, the multilayer reflective film preferably has the highest surface layer (the uppermost layer) as a high refractive index layer. This is because the low refractive index layer is easily oxidized, so that if the low refractive index layer becomes the uppermost layer of the reflective layer 12, the reflectance of the reflective layer 12 may decrease.

As the high refractive index layer, a layer containing Si can be used. As the material containing Si, in addition to Si alone, a Si compound containing at least one member selected from the group consisting of B, C, N and O can be used for Si. By using the high refractive index layer containing Si, the reflective mask excellent in the reflectance of EUV light is obtained. As the low refractive index layer, metals selected from the group consisting of Mo, Ru, Rh and Pt or alloys thereof can be used. In this embodiment, it is preferable that the low refractive index layer is a layer containing Mo, and the high refractive index layer is a layer containing Si. In this case, the uppermost layer of the reflective layer 12 is a high refractive index layer (layer containing Si), so that silicon oxide containing Si and O is contained between the uppermost layer (layer containing Si) and the protective layer 13. The layer is formed to improve the cleaning resistance of the reflective mask.

Although the reflective layer 12 is provided with two or more high refractive index layers, respectively, the film thickness of a high refractive index layer or the film thickness of a low refractive index layer does not necessarily need to be the same.

The film thickness and the period of each layer constituting the reflective layer 12 can be appropriately selected according to the film material to be used, the reflectance of EUV light required for the reflective layer 12, the wavelength of the EUV light (exposure wavelength), or the like. For example, when the reflecting layer 12 sets the maximum value of the reflectance of EUV light near wavelength 13.5 nm to 60% or more, the low refractive index layer (layer containing Mo) and the high refractive index layer (layer containing Si) are alternated. A Mo / Si multilayer reflective film laminated 30 to 60 cycles is preferably used.

In addition, each layer which comprises the reflective layer 12 can be formed into a desired film thickness using well-known film-forming methods, such as a magnetron sputtering method and an ion beam sputtering method. For example, when manufacturing the reflective layer 12 using the ion beam sputtering method, it is performed by supplying ion particle from an ion source with respect to the target of a high refractive index material, and the target of a low refractive index material. When the reflective layer 12 is a Mo / Si multilayer reflective film, a layer containing Si having a predetermined film thickness is formed on the substrate 11 by ion beam sputtering, for example, first using a Si target. Then, using Mo target, the layer containing Mo of predetermined film thickness is formed into a film. The Mo / Si multilayer reflective film is formed by laminating 30 to 60 cycles of the Si-containing layer and the Mo-containing layer in one cycle.

(Protective layer)

In the manufacturing of the reflective mask 20 (see FIG. 5), which will be described later, the protective layer 13 is etched (usually dry etched) from the absorber layer 14 to the absorber pattern 141 (FIG. 5), the surface of the reflective layer 12 is prevented from being damaged by etching, thereby protecting the reflective layer 12. In addition, the resist layer 19 (refer to FIG. 6) remaining in the reflective mask blank after etching is peeled off with the cleaning liquid, and the reflective layer 12 is protected from the cleaning liquid when the reflective mask blank is cleaned. Therefore, the reflectance with respect to EUV light of the reflective mask 20 (refer FIG. 5) obtained becomes favorable.

Although the case where the protective layer 13 is one layer is shown in FIG. 1, the protective layer 13 may be multiple layers.

As a material for forming the protective layer 13, a material that is less likely to be damaged by etching at the time of etching the absorber layer 14 is selected. As a material which satisfies this condition, for example, Ru metal contains Ru at least one metal selected from the group consisting of B, Si, Ti, Nb, Mo, Zr, Y, La, Co and Re. Ru-based materials such as a Ru alloy and a nitride containing nitrogen in the Ru alloy; Nitrides containing nitrogen in Cr, Al, Ta and these; SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ or mixtures thereof and the like are exemplified. Among these, single Ru metal, Ru alloy, CrN, and SiO ₂ are preferable. The Ru metal alone and the Ru alloy are particularly preferable because they are difficult to be etched with respect to a gas containing no oxygen and function as an etching stopper at the time of processing the reflective mask.

When the protective layer 13 is formed of Ru alloy, the Ru content in the Ru alloy is preferably 95 at% or more and less than 100 at%. If the Ru content is within the above range, when the reflective layer 12 is a Mo / Si multilayer reflective film, it is possible to suppress the diffusion of Si into the protective layer 13 from the Si layer of the reflective layer 12. In addition, the protective layer 13 can have a function as an etching stopper when the absorption layer 14 is etched while sufficiently securing the reflectance of EUV light. In addition, the reflective mask may have cleaning resistance and at the same time prevent deterioration of the reflective layer 12.

The film thickness of the protective layer 13 is not particularly limited as long as it can function as the protective layer 13. In view of maintaining the reflectance of the EUV light reflected by the reflective layer 12, the film thickness of the protective layer 13 is preferably 1 nm or more, more preferably 1.5 nm or more, and even more preferably 2 nm or more. 8 nm or less is preferable, as for the film thickness of the protective layer 13, 6 nm or less is more preferable, 5 nm or less is further more preferable.

As the formation method of the protective layer 13, a well-known film formation method, such as a magnetron sputtering method or an ion beam sputtering method, can be used.

(Absorption layer)

In order to be used for the reflective mask of EUV lithography, the absorbing layer 14 needs to have characteristics such as high absorption coefficient of EUV light, easy etching and high cleaning resistance to the cleaning liquid.

The absorption layer 14 absorbs EUV light, and the reflectance of EUV light is very low. Specifically, 2% or less is preferable and, as for the maximum value of the reflectance of EUV light of wavelength 13.5 nm vicinity when EUV light is irradiated to the surface of the absorption layer 14, 1% or less is more preferable. Therefore, the absorption layer 14 needs to have high absorption coefficient of EUV light.

The absorber layer 14 is processed by etching by dry etching using chlorine (Cl) gas such as Cl ₂ , SiCl ₄ and CHCl ₃ or fluorine (F) gas such as CF ₄ or CHF ₃ . Therefore, the absorbing layer 14 needs to be able to be easily etched.

In addition, in the manufacturing of the reflective mask 20 (refer FIG. 5) mentioned later, the absorption layer 14 can remove the resist pattern 191 (refer FIG. 6) which remains in the reflective mask blank after an etching with a washing | cleaning liquid. At the time of exposure to the cleaning liquid. At that time, sulfuric acid fruit water (SPM), sulfuric acid, ammonia, ammonia fruit water (APM), OH radical washing water, ozone water and the like are used as the cleaning liquid. In EUV lithography, SPM is generally used as a cleaning liquid of a resist. In addition, SPM is a solution which mixed sulfuric acid and hydrogen peroxide, for example, is a solution which mixed sulfuric acid and hydrogen peroxide in the ratio of 3: 1 by volume ratio. At this time, it is preferable to control the temperature of SPM to 100 degreeC or more from the point which improves an etching rate. Therefore, the absorbing layer 14 needs to raise the washing | cleaning tolerance with respect to a washing | cleaning liquid. The absorbing layer 14 preferably has a low etching rate (for example, 0.10 nm / minute or less) when immersed in a 100 ° C. solution having 75 vol% sulfuric acid and 25 vol% hydrogen peroxide.

In order to achieve the above characteristics, the absorber layer 14 contains Sn. Since Sn has a large absorption coefficient, the absorption layer 14 can contain Sn, thereby making it possible to lower the reflectance of the absorption layer 14. In addition, the absorber layer 14 can be easily etched with Cl gas or the like by containing Sn.

The absorber layer 14 preferably contains Ta, Cr or Ti in addition to Sn. These elements may be included individually by 1 type, and may contain 2 or more types. The absorber layer 14 further contains at least one of these elements in addition to Sn, thereby increasing the cleaning resistance.

The absorber layer 14 may further contain N, B, Hf or H in addition to Sn. These elements may be included individually by 1 type, and may contain 2 or more types. In particular, the absorber layer 14 preferably includes at least one of N or B among these elements. The absorber layer 14 includes at least one of N or B, whereby the crystal state of the absorber layer 14 can have an amorphous or microcrystalline structure.

The preferable composition of the absorber layer 14 is SnTa, SnTaN, SnTaB, or SnTaBN, for example.

It is preferable that the absorption layer 14 is amorphous. As a result, the absorber layer 14 may have excellent smoothness and flatness. In addition, by improving the smoothness and flatness of the absorber layer 14, the edge roughness of the absorber pattern 141 (see FIG. 5) is reduced, and the dimensional accuracy of the absorber pattern 141 (see FIG. 5) can be increased. have.

The absorption layer 14 may be a single layer film or a multilayer film including a plurality of films. When the absorption layer 14 is a single | mono layer film, the number of processes at the time of mask blank manufacture can be reduced, and production efficiency can be improved. When the absorber layer 14 is a multilayer film, by setting the optical constant and the film thickness of the layer on the upper layer side of the absorber layer 14 appropriately, the layer on the upper layer side of the absorber layer 14 uses the absorbing light pattern 141. ) (See Fig. 5) can be used as an antireflection film. Thereby, the inspection sensitivity at the time of the inspection of an absorber pattern can be improved.

Although the film thickness of the absorber layer 14 can be designed suitably according to the composition of the absorber layer 14, etc., a thinner one is preferable at the point which suppresses the influence of shadowing. The film thickness of the absorber layer 14 is preferably 40 nm or less, for example, from the viewpoint of obtaining sufficient contrast while maintaining the reflectance of the absorber layer 14 at 1% or less. As for the film thickness of the absorber layer 14, 35 nm or less is more preferable, 30 nm or less is more preferable, 25 nm or less is more preferable, 20 nm or less is especially preferable. The film thickness of the absorber layer 14 is determined by reflectance, and the thinner the better. The film thickness of the absorber layer 14 can be measured using X-ray reflectance method (XRR), TEM, etc., for example.

The absorption layer 14 can be formed using a well-known film formation method, such as a magnetron sputtering method and an ion beam sputtering method. For example, when forming a SnTa film using the magnetron sputtering method as the absorbing layer 14, the absorbing layer 14 can be formed by the sputtering method using Ar gas, using the target containing Sn and Ta. have. In addition, the absorption layer 14 can be formed also by the binary sputtering method which uses a Sn target and a Ta target simultaneously.

(Prevention layer)

The prevention layer 15 is formed on the main surface above the absorption layer 14 (+ Z-axis direction).

As the material for forming the prevention layer 15, Ta, Ru, Cr, Ti or Si can be used. These elements may be contained individually by 1 type, and may be contained 2 or more types.

The prevention layer 15 is formed of Ta, Ru, Cr, Ti, Si, Ta, Ta, Ni, Cr, Ti, Si, Ta, boride, Ru, A boride of Cr, a boride of Ti, a boride of Si, or a boron nitride of Ta can be used. These may be contained individually by 1 type and may be contained 2 or more types.

The preferable composition of the prevention layer 15 is Ta, TaN, TaB, or TaBN, for example. For example, as will be described later, the reflective mask blank 10B (see FIG. 7) according to the second embodiment having the stable layer 21 on the prevention layer 15 is formed. It is assumed that the stable layer 21 contains an oxide, oxynitride or oxyboride containing Ta. In this case, if the prevention layer 15 is these materials, the same target can be used when forming the prevention layer 15 and the stabilizer layer 21. Therefore, productivity of the reflective mask blank 10B (refer FIG. 7) is excellent, such that the number of film-forming chambers required can be reduced.

The prevention layer 15 may also contain elements, such as He, Ne, Ar, Kr, or Xe.

The prevention layer 15 is a layer containing no Sn and oxygen. The absence of Sn and oxygen means that Sn and oxygen do not exist on the surface and inside of the prevention layer 15 immediately after the formation of the prevention layer 15. When the prevention layer 15 is exposed in an atmosphere containing oxygen, the components contained in the prevention layer 15 react (oxidize) with oxygen on the surface where the prevention layer 15 is in contact with oxygen, thereby causing the surface of the prevention layer 15 to react. An oxide film may be produced in some cases. At this time, if Sn is contained in the prevention layer 15, Sn which exists on the surface of the prevention layer 15 reacts with oxygen, and microparticles | fine-particles containing Sn, such as tin oxide, are formed as a precipitate on the surface of the prevention layer 15 as a precipitate. Since there is a possibility of occurrence, the prevention layer 15 does not contain Sn.

In addition, when the prevention layer 15 contains the film | membrane of the oxide produced in the surface which contacted with the oxygen in the process after forming the prevention layer 15, the prevention layer 15 does not contain oxygen. Oxygen included is not included. On the other hand, since the interface of the absorption layer 14 and the prevention layer 15 does not contact oxygen, oxygen is not contained in the interface of the prevention layer 15 and the absorption layer 14.

The prevention layer 15 can be formed in an inert gas atmosphere or in a gas atmosphere in which nitrogen is selectively added to the inert gas using a known film formation method such as a magnetron sputtering method or an ion beam sputtering method. For example, when forming a Ta film, a Ru film, a Cr film, or a Si film using the magnetron sputtering method as the prevention layer 15, a target containing Ta, Ru, Cr or Si is used, and as a sputter gas, The prevention layer 15 is formed by using an inert gas such as He, Ar or Kr, or a gas in which nitrogen is selectively added to the inert gas.

If the prevention layer 15 is too thick, the film thickness of the prevention layer 15 takes time to etch the prevention layer 15. In addition, there is a possibility that shadowing or the like becomes large. On the other hand, if the prevention layer 15 is too thin, there is a possibility that the function as the prevention layer 15 cannot be sufficiently exhibited stably. Therefore, the film thickness of the prevention layer 15 should just be a few nm in the point which suppresses the thickness of the pattern of the reflective mask blank 10A, and it is preferable that it is 10 nm or less. As for the film thickness of the prevention layer 15, 8 nm or less is more preferable, 6 nm or less is more preferable, 5 nm or less is more preferable, 4 nm is especially preferable. As for the film thickness of the prevention layer 15, 0.5 nm or more is more preferable, 1 nm or more is more preferable, 1.5 nm or more is more preferable, 2 nm or more is especially preferable. The film thickness of the prevention layer 15 can be measured using XRR, TEM, etc., for example.

As described above, the reflective mask blank 10A has the prevention layer 15 on the absorbing layer 14 containing Sn. When the absorber layer 14 is in contact with oxygen, some Sn present on the surface of the absorber layer 14 reacts with oxygen, and fine particles containing Sn, including tin oxide or the like, are formed on the surface of the absorber layer 14. It may occur as a precipitate. As described above, the prevention layer 15 is formed on the absorption layer 14 by using only an inert gas such as He, Ar or Kr, or a gas in which nitrogen is selectively added to the inert gas. Therefore, by forming the prevention layer 15 before the absorption layer 14 contacts gas, such as oxygen, it can prevent that the absorption layer 14 is in contact with oxygen. Thereby, the surface of the absorbing layer 14 is oxidized, and it can prevent that a precipitate generate | occur | produces on the surface of the absorbing layer 14, and it can suppress that a defect arises on the surface of the absorbing layer 14

Therefore, when the reflective mask 20 (refer FIG. 5) is produced using the reflective mask blank 10A, it can suppress that a defect arises in the reflective mask 20 (refer FIG. 5). Therefore, when the reflective mask blank 10A is used, a pattern free of defects can be stably formed.

The reflective mask blank 10A may form the prevention layer 15 including at least one element of Ta, Ru, Cr or Si. These elements are easy to dry etch and are excellent in cleaning resistance. Therefore, when the prevention layer 15 is comprised of Ta etc., even if the absorption layer 14 contains Sn, the absorber pattern 141 which is strong in washing resistance will be prevented, while preventing the oxidation of the surface of the absorption layer 14 (FIG. 5). Reference).

The reflective mask blank 10A is formed of a protective layer 15 of Ta, Ru, Cr, Si, Si, Ta, Ni, Cr, Ni, Si, Ta, and Bor. , Boride of Cr, boride of Si, or boron nitride of Ta. Since these single substance, nitride, boride, and boron nitride are amorphous, the edge roughness of the absorber pattern 141 (refer FIG. 5) can be suppressed. Therefore, when the prevention layer 15 is formed of Ta nitride or the like, a highly accurate absorber pattern 141 (see FIG. 5) can be formed while preventing surface oxidation of the absorber layer 14 containing Sn. .

The reflective mask blank 10A may be formed on the prevention layer 15 by including at least one element of He, Ne, Ar, Kr or Xe. When these elements are used as the sputter gas at the time of film formation of the prevention layer 15, a trace amount of these elements may be contained in the prevention layer 15 in some cases. Also in this case, the function of the prevention layer 15 can be exhibited without affecting the property of the prevention layer 15.

The reflective mask blank 10A can make the film thickness of the prevention layer 15 into 10 nm or less. Thereby, since the thickness of the prevention layer 15 can be suppressed, the reflective mask blank 10A uses the absorber pattern 141 (refer FIG. 5), and the thickness of the whole pattern of the prevention layer 15 formed on it. It can be suppressed.

The reflective mask blank 10A can comprise the absorption layer 14 including one or more elements selected from the group consisting of Ta, Cr and Ti. By including these elements in the absorbent layer 14, the washing resistance of the absorbent layer 14 can be further improved, and the absorbent layer 14 can be made thinner. As a result, even if it is thin, the absorption layer 14 with high absorption rate of EUV light can be obtained. Therefore, the reflectance of EUV light in the absorbing layer 14 can be made low while thinning the reflective mask blank 10A and thinning the pattern of the reflective mask 20 (see FIG. 5).

The reflective mask blank 10A is preferably provided with a protective layer 13 between the reflective layer 12 and the absorbing layer 14. Thereby, the reflective layer 12 can be protected at the time of manufacturing the reflective mask 20 (refer FIG. 5) at the time of etching the absorbing layer 14 and cleaning a reflective mask blank. Therefore, the reflectance with respect to EUV light of the reflective mask 20 (refer FIG. 5) obtained can be made favorable.

<Method for producing reflective mask blank>

Next, the manufacturing method of the reflective mask blank 10A shown in FIG. 1 is demonstrated. 2 is a flowchart illustrating an example of a method of manufacturing the reflective mask blank 10A.

As shown in FIG. 2, the reflective layer 12 is formed on the board | substrate 11 (the formation process of the reflective layer 12: step S11). The reflective layer 12 is formed on the substrate 11 to have a desired film thickness by using a known film forming method as described above.

Next, the protective layer 13 is formed on the reflective layer 12 (formation process of the protective layer 13: step S12). The protective layer 13 is formed on the reflective layer 12 using a known film formation method so as to have a desired film thickness.

Next, the absorption layer 14 is formed on the protective layer 13 (formation process of the absorption layer 14: step S13). The absorber layer 14 is formed on the protective layer 13 using a known film formation method so as to have a desired film thickness. For example, the absorption layer 14 can be formed in the film formation chamber of a film-forming apparatus using a well-known film-forming apparatus.

In addition, after the absorption layer 14 is formed, it is taken out from the film formation chamber of the film forming apparatus used for the formation of the absorption layer 14 and transferred to the storage chamber. Then, the inside of the storage chamber is in a high vacuum state, for example, on the absorption layer 14, the prevention layer ( 15) may be stored until use, for example.

Next, the prevention layer 15 is formed on the absorption layer 14 (formation process of the prevention layer 15: step S14). The prevention layer 15 is formed into a desired film thickness in an inert gas atmosphere or a gas atmosphere in which nitrogen is selectively added to the inert gas using a well-known film formation method on the absorber layer 14.

Thereby, the reflective mask blank 10A as shown in FIG. 1 is obtained.

In addition, in this embodiment, the manufacturing method of the reflective mask blank 10A can perform the formation process (step S13) of the absorption layer 14, and the formation process (step S14) of the prevention layer 15 in succession. . In this case, the binary sputtering method using the target, such as metal which comprises the absorption layer 14, such as Sn target, and the target, such as metal which comprises the prevention layer 15, such as Ta target, can be used. By using the binary sputtering method, the charge to the target such as the metal constituting the absorbing layer 14 is terminated earlier than the charge to the target such as the metal constituting the prevention layer 15, so that in the film forming room of the film forming apparatus, Formation of the absorption layer 14 and formation of the prevention layer 15 can be performed continuously.

(Other layers)

As shown in FIG. 3, the reflective mask blank 10A may include a hard mask layer 17 on the prevention layer 15. As the hard mask layer 17, a material having high resistance to etching such as a Cr-based film, a Si-based film, or a Ru-based film is used.

As Cr type film | membrane, the substance etc. which added O or N to Cr single substance and Cr are mentioned, for example. Specifically, CrO, CrN, CrON, etc. are mentioned.

As Si type film | membrane, the material etc. which added 1 or more types chosen from the group which consists of Si single-piece | units and O, N, C, and H are mentioned. Specifically, there may be mentioned _{SiO 2, SiON, SiN, SiO} , Si, SiC, SiCO, SiCN and SiCON. Among them, the Si-based film is preferable because retreat of the sidewall hardly occurs when dry-etching the absorber layer 14.

As Ru type | system | group film, the material etc. which added O or N to Ru and Ru are mentioned, for example. Specifically, RuO, RuN, RuON, etc. are mentioned.

By forming the hard mask layer 17 on the prevention layer 15, even if the minimum line width of the absorber pattern 141 becomes small, dry etching can be performed. Therefore, it is effective for miniaturization of the absorber pattern 141. In addition, when another layer is laminated | stacked on the prevention layer 15, the hard mask layer 17 should just be provided on the layer of the outermost surface side of the prevention layer 15. As shown in FIG.

As shown in FIG. 4, the reflective mask blank 10A has a back conductive layer 18 for an electrostatic chuck on the second main surface 11b on the side opposite to the side on which the reflective layer 12 of the substrate 11 is stacked. It may be provided. As the property, the back surface conductive layer 18 is required to have a low sheet resistance value. The sheet resistance value of the back surface conductive layer 18 is 250 ohms / square or less, for example, and 200 ohms / square or less is preferable.

As the material including the back conductive layer 18, for example, a metal such as Cr or Ta or an alloy thereof can be used. As the alloy containing Cr, a Cr compound containing at least one member selected from the group consisting of B, N, O and C can be used for Cr. As a Cr compound, CrN, CrON, CrCN, CrCON, CrBN, CrBON, CrBCN, CrBOCN, etc. are mentioned, for example. As the alloy containing Ta, a Ta compound containing at least one member selected from the group consisting of B, N, O and C can be used for Ta. Examples of Ta compounds include TaB, TaN, TaO, TaON, TaCON, TaBN, TaBO, TaBON, TaBCON, TaHf, TaHfO, TaHfN, TaHfON, TaHfCON, TaSi, TaSiO, TaSiN, TaSiON, TaSiCON, and the like. .

Although the film thickness of the back surface conductive layer 18 is not specifically limited as long as the function as an electrostatic chuck is fulfilled, it shall be 10-400 nm, for example. In addition, this back surface conductive layer 18 can also be equipped with the stress adjustment of the 2nd main surface 11b side of the reflective mask blank 10A. That is, the back surface conductive layer 18 can be adjusted to balance the stress from the various layers formed on the first main surface 11a side, and to make the reflective mask blank 10A flat.

As the formation method of the back surface conductive layer 18, well-known film-forming methods, such as a magnetron sputtering method or an ion beam sputtering method, can be used.

The back surface conductive layer 18 can be formed in the 2nd main surface 11b of the board | substrate 11, for example before forming the protective layer 13. As shown in FIG.

<Reflective mask>

Next, the above-described reflective mask obtained by using the reflective mask blank 10A shown in FIG. 1 will be described. 5 is a schematic cross-sectional view showing an example of the configuration of the reflective mask. As shown in FIG. 5, the reflective mask 20 forms the desired absorber pattern 141 in the absorption layer 14 of the reflective mask blank 10A shown in FIG.

An example of the manufacturing method of the reflective mask 20 is demonstrated. 6 is a view for explaining a manufacturing process of the reflective mask 20. As shown in Fig. 6A, a resist layer 19 is formed on the absorption layer 14 of the reflective mask blank 10A shown in Fig. 1 described above.

Thereafter, a desired pattern is exposed to the resist layer 19. After exposure, the exposed portion of the resist layer 19 is developed and washed (rinsed) with pure water, thereby forming a predetermined resist pattern 191 on the resist layer 19 as shown in FIG. do.

Thereafter, the absorber layer 14 is dry etched using the resist layer 19 on which the resist pattern 191 is formed as a mask. As a result, as shown in FIG. 6C, an absorber pattern 141 corresponding to the resist pattern 191 is formed in the absorbing layer 14.

As the etching gas, an F-based gas, a Cl-based gas, a Cl-based gas, and a mixed gas containing O ₂ , He, or Ar at a predetermined ratio can be used.

Thereafter, the resist layer 19 is removed using a resist stripping solution or the like to form a desired absorber pattern 141 on the absorber layer 14. Thereby, as shown in FIG. 5, the reflective mask 20 in which the desired absorber pattern 141 was formed in the absorption layer 14 can be obtained.

EUV light is irradiated to the obtained reflective mask 20 from the illumination optical system of the exposure apparatus. EUV light incident on the reflective mask 20 is reflected at the portion without the absorber layer 14 (part of the absorber pattern 141) and absorbed at the portion with the absorber layer 14. As a result, the reflected light of the EUV light reflected by the absorption layer 14 is irradiated to the exposure material (for example, wafer) through the reduced projection optical system of the exposure apparatus. As a result, the absorber pattern 141 of the absorber layer 14 is transferred onto the exposure material, and a circuit pattern is formed on the exposure material.

Second Embodiment

The reflective mask blank according to the second embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the member which has the same function as the said embodiment, and detailed description is abbreviate | omitted.

7 is a schematic cross-sectional view of the reflective mask blank according to the second embodiment. As shown in FIG. 7, the reflective mask blank 10B has a stabilizer layer 21 on the prevention layer 15 of the reflective mask blank 10A shown in FIG. 1. That is, in the reflective mask blank 10B, the substrate 11, the reflective layer 12, the protective layer 13, the absorption layer 14, the prevention layer 15, and the stabilizer layer 21 are arranged in this order from the substrate 11 side. It is laminated as it is and is comprised.

As the stable layer 21, oxides, oxynitrides and oxyborides containing Ta can be used. Examples of the oxides, oxynitrides, and oxyborides containing Ta include TaO, Ta ₂ O ₅ , TaON, TaCON, TaBO, TaBON, TaBCON, TaHfO, TaHfON, TaHfCON, TaSiO, TaSiON, TaSiCON, and the like. .

As for the film thickness of the stable layer 21, 10 nm or less is preferable. As for the film thickness of the stable layer 21, 7 nm or less is more preferable, 6 nm or less is more preferable, 5 nm or less is more preferable, 4 nm or less is especially preferable. 1 nm or more is more preferable, as for the film thickness of the stable layer 21, 2 nm or more is more preferable, and 3 nm or more is especially preferable.

The stable layer 21 can be formed using a well-known film-forming method, such as a magnetron sputtering method and an ion beam sputtering method.

As described above, the reflective mask blank 10B has a stabilizing layer 21 on the prevention layer 15, whereby the cleaning resistance of the prevention layer 15 can be further improved. By having the stabilizer layer 21, a firm and stable film can be formed with good reproducibility, and the characteristics of the reflective mask blank and the reflective mask can be stabilized.

Since the reflective mask blank 10B has the prevention layer 15 on the absorption layer 14 containing Sn, when the stable layer 21 is formed on the prevention layer 15, the surface of the absorption layer 14 is There is no contact with oxygen. For example, when the stable layer 21 is formed using the reactive sputtering method, as described above, the sputtering gas may be a mixed gas in which oxygen is mixed with an inert gas such as He, Ar, or Kr, or an inert gas. Nitrogen is optionally added, and a mixed gas in which oxygen is mixed is used. Since the prevention layer 15 is formed on the absorption layer 14, when forming the stable layer 21, the surface of the absorption layer 14 does not contact the mixed gas which is sputter gas. Therefore, the surface of the absorption layer 14 does not oxidize, and it can prevent that a precipitate generate | occur | produces on the surface of the absorption layer 14.

Since the reflective mask blank 10B is formed using an oxide, oxynitride or oxyboride containing Ta, the composition in the stabilized layer 21 is not generated by washing, and therefore, moreover, A reflective mask blank and a reflective mask excellent in the wash resistance can be obtained.

The reflective mask blank 10B has a film thickness of the stabilization layer 21 of 10 nm or less, thereby making the reflective mask blank 10B thin and the pattern thin film of the reflective mask while washing resistance of the prevention layer 15. I can keep it.

In addition, as shown in FIG. 8, the reflective mask blank 10B is similar to the reflective mask blank 10A according to the first embodiment shown in FIG. 4. The hard mask layer 10B is formed on the stable layer 21. 17) may be provided.

EXAMPLE

Example 1 is a comparative example, and Examples 2-4 are Examples.

[Example 1]

The reflective mask blank 100 is shown in FIG. 9. The reflective mask blank 100 does not have the prevention layer 15 on the absorption layer 14 in the reflective mask blank 10A according to the first embodiment shown in FIG. 1.

(Production of reflective mask blank)

As the substrate for film formation, a glass substrate of SiO ₂ -TiO _{2 type} (square having an outer side of about 152 mm and thickness of about 6.3 mm) was used. In addition, the thermal expansion coefficient of the glass substrate was 0.02x10 <^-7> / degreeC or less. The glass substrate was polished, and the surface roughness was processed to a smooth surface of 0.15 nm or less with a root mean square roughness Rq and flatness of 100 nm or less. On the back surface of the glass substrate, a Cr layer having a film thickness of about 100 nm was formed by using a magnetron sputtering method to form a back conductive layer (conductive film) for an electrostatic chuck. The sheet resistance of the Cr layer was about 100 Ω / square. After fixing a glass substrate using a Cr film, 40 cycles of repeating film formation of an Si film and an Mo film were repeated using the ion beam sputtering method on the surface of the glass substrate. The film thickness of the Si film was about 4.5 nm, and the film thickness of the Mo film was about 2.3 nm. As a result, a total film thickness of about 272 nm ((Si film: 4.5 nm + Mo film: 2.3 nm) x 40) was formed to form a reflective layer (multilayer reflective film). Thereafter, a Ru layer (film thickness of about 2.5 nm) was formed on the reflective layer by using an ion beam sputtering method to form a protective layer (protective film). Subsequently, an absorbing layer (absorber film) having a thickness of 40 nm containing an Sn—Ta alloy was formed on the protective layer by a magnetron sputtering method. Ar gas was used as the sputter gas. Sn used for the sputter | spatter was 60at% of Sn and 40at% of Ta, but Ta content in the sputtered absorption layer was 48at%. In addition, Sn content and Ta content in an absorption layer were measured using the fluorescence X-ray spectroscopy (XRF) (Olympus company Delta). This produced the reflective mask blank 100 shown in FIG. The film thickness of the absorbing layer was measured by XRR using an X-ray diffractometer (manufactured by Rigaku Corporation, SmartLab HTP). Moreover, from the X-ray diffraction (XRD) measurement result using the same apparatus, it was confirmed that the absorption layer containing Sn-Ta alloy is amorphous.

(Observation of the surface of the reflective mask blank)

The surface of the reflective mask blank 100 was observed using a scanning electron microscope (Ultra60, manufactured by Carl Zeiss). The observation result of the surface of a reflective mask blank is shown in FIG. As shown in FIG. 10, fine particles were observed on the surface of the reflective mask blank. As a result of analyzing the fine particles by energy dispersive X-ray analysis (EDX), it was confirmed that the fine particles were formed of tin oxide. The fine particles on the surface of the absorber layer are considered to be generated when Sn contained in the absorber layer reacts with oxygen in the air when the absorber layer is exposed to the atmosphere. Such fine particles are not preferable because they may remain as pattern defects in the reflective mask after etching of the absorbing layer.

[Example 2]

In this example, 4 nm of the TaN film which becomes a prevention layer was formed into a film on the absorption layer of the reflective mask blank 100 produced in Example 1, and the reflective mask blank 10A shown in FIG. 1 was produced. In addition, the prevention layer used the reactive sputtering method and used the mixed gas which mixed Ar and nitrogen as a sputter gas, the flow volume of Ar was 70 sccm, and the flow volume of nitrogen was 2 sccm. In addition, the reflective mask blank 100 produced in Example 1 was transferred to the storage chamber from the deposition chamber of the film-forming apparatus used for the formation of the absorption layer until the prevention layer was formed on the absorption layer, and the storage chamber was kept in a high vacuum state. It was.

(Observation of the surface of the reflective mask blank)

The surface of the reflective mask blank 10A was observed using a scanning electron microscope. The observation result of the surface of the absorption layer of the reflective mask blank 10A is shown in FIG. As shown in FIG. 11, microparticles | fine-particles did not generate | occur | produce on the surface of the absorption layer of the reflective mask blank 10A. This is because the prevention layer is present on the surface of the absorber layer, so that oxygen in the atmosphere does not contact Sn contained in the absorber layer.

Example 3

In this example, a protective layer containing Ta is formed by a magnetron sputtering method on the absorption layer of the reflective mask blank 100 produced in Example 1 by 2 nm, and a stable layer containing TaO is formed on the protective layer by reactive sputtering. 2 nm film-forming was carried out using the method. This produced the reflective mask blank 10B shown in FIG. In addition, when forming a prevention layer using the magnetron sputtering method, Ar gas was used for sputter gas. When forming a stable layer using the reactive sputtering method, the mixed gas which mixed Ar and oxygen was used as sputter gas, the flow volume of Ar was 40 sccm, and the flow volume of oxygen was 30 sccm. In addition, the reflective mask blank 100 produced in Example 1 was transferred from the deposition chamber of the film deposition apparatus used for the formation of the absorption layer to the storage chamber until the prevention layer was formed on the absorption layer, and the inside of the storage chamber was kept in a high vacuum state. .

The film thickness of Ta was 0.9 nm and TaO was 4.6 nm when the prevention layer and the stable layer of the reflective mask blank 10B after film-forming were measured by XRR. It is considered that this is because when TaO film is formed on the Ta film, oxygen contained in the sputter gas and Ta of the Ta film react to form a TaO film and expand.

Thereafter, the reflective mask blank 10B shown in FIG. 7 was dry etched using a dry etching apparatus. After dry etching removed the prevention layer and the stable layer using F type gas, the absorption layer was removed using Cl type gas.

(Observation of the surface of the reflective mask blank)

The surface of the reflective mask blank 10B was observed using a scanning electron microscope. The observation result of the absorption layer of the surface of the reflective mask blank 10B is shown in FIG. As shown in Fig. 12, no precipitates such as fine particles were observed on the surface of the reflective mask blank. In this example, only Ar is used as the sputtering gas for forming the prevention layer. Therefore, since the surface of the absorbent layer is not exposed to an atmosphere containing oxygen, Sn present on the surface of the absorbent layer does not react with oxygen. Thereby, it can be said that generation | occurrence | production of a precipitate on the surface of an absorption layer was suppressed.

Example 4

(Production of reflective mask blank)

In this example, in Example 3, when forming the absorption layer containing a Sn-Ta alloy, the binary sputtering method which uses a Sn target and a Ta target simultaneously was used instead of a Sn-Ta alloy target. Ar gas was used for the sputter gas, the flow rate of Ar was 70 sccm, and the input power to the Sn target was 130 W, and the input power to the Ta target was 200 W. When binary sputtering was performed, charging to the Sn target and the Ta target was simultaneously started. The end time of the charge to the Sn target and the Ta target was 520 seconds after the charge start on the Sn target, and 608 seconds after the charge start on the Ta target. Thereby, the prevention layer of the film thickness of 2 nm containing Ta was formed continuously in one sputter | spatter on the absorption layer of 35-nm-thick film containing Sn-Ta alloy, and the absorption layer. Then, 2 nm of stable layers containing TaO were formed on the prevention layer similarly to Example 3 using the reactive sputtering method. This produced the reflective mask blank 10B shown in FIG. Moreover, it was 35% when the Ta content in the sputtered absorption layer was measured using XRF.

(Observation of the surface of the reflective mask blank)

When the surface of the reflective mask blank 10B produced in this example was observed using a scanning electron microscope, no precipitates such as fine particles were observed on the surface of the reflective mask blank 10B. As in Example 2 or Example 3, when the absorption layer and the prevention layer are formed by two sputtering, from the deposition chamber of the film forming apparatus, the reflective mask blank 100 formed by forming the absorption layer in Example 1 is used for formation of the absorption layer. You need to revert to. Although the storage chamber is maintained at high vacuum, there is a risk that oxide fine particles are generated on the surface of the absorbing film by oxygen remaining in a small amount. In this example, since the absorption layer and the prevention layer are formed into a film continuously in the film formation chamber of the film forming apparatus, and the reflective mask blank 10B is produced, the generation of fine particles of oxide in the storage chamber can be reduced. In addition, since one sputter is used, the production time of the reflective mask blank 10B can be shortened.

As mentioned above, although embodiment was described, the said embodiment is shown as an example and this invention is not limited by the said embodiment. The above embodiments can be implemented in other various forms, and various combinations, omissions, substitutions, changes, and the like can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and spirit of the invention, and are included in the inventions described in the claims and their equivalents.

This application claims the priority based on Japanese Patent Application No. 2018-112601 for which it applied to Japan Patent Office on June 12, 2018, and uses the whole content of Japanese Patent Application 2018-112601 for this application.

10A, 10B: Reflective Mask Blank
11: substrate
12: reflective layer
13: protective layer
14: absorption layer
15: prevention layer
17: hard mask layer
18: back side conductive layer
19: resist layer
20: reflective mask
21: stable layer

Claims (15)

It is a reflective mask blank which has on a board | substrate the reflecting layer which reflects EUV light, and the absorbing layer which absorbs EUV light in this order from a board | substrate side,
The absorbent layer contains Sn,
A reflective mask blank having a prevention layer on the absorption layer to prevent oxidation of the absorption layer. The reflective mask blank of claim 1, wherein the prevention layer contains at least one element selected from the group consisting of Ta, Ru, Cr, Ti, and Si, and does not contain Sn and oxygen. The Ti layer, Ru group, Cr group, Ti group, Si group, nitride of Ta, nitride of Ru, nitride of Cr, nitride of Ti, nitride of Si, boride of Ta, A reflective mask blank containing at least one component selected from the group consisting of boride of Ru, boride of Cr, boride of Ti, boride of Si, and boron nitride of Ta. The reflective mask blank according to any one of claims 1 to 3, wherein the prevention layer contains at least one element selected from the group consisting of He, Ne, Ar, Kr, and Xe. The reflective mask blank according to any one of claims 1 to 4, wherein the prevention layer has a film thickness of 10 nm or less. The reflective mask blank according to any one of claims 1 to 5, wherein the absorbing layer contains at least one element selected from the group consisting of Ta, Cr, and Ti. The reflective mask blank according to any one of claims 1 to 6, further comprising a stable layer on the prevention layer. The reflective mask blank according to claim 7, wherein the stable layer contains at least one member selected from the group consisting of Ta, oxide, oxynitride and oxyboride. The reflective mask blank according to claim 7 or 8, wherein the stable layer has a thickness of 10 nm or less. 10. The reflective mask blank according to any one of claims 1 to 9, having a protective layer between the reflective layer and the absorbing layer. The reflective mask blank according to any one of claims 1 to 10, further comprising a hard mask layer on the barrier layer or on a layer on the outermost surface side of the barrier layer. The reflective mask blank of claim 11, wherein the hard mask layer comprises at least one element selected from the group consisting of Cr, Si, and Ru. The reflective mask in which the pattern is formed in the said absorption layer of the reflective mask blank of any one of Claims 1-12. It is a manufacturing method of the reflective mask blank which has on a board | substrate the reflecting layer which reflects EUV light, and the absorption layer which absorbs EUV light in this order from the said board | substrate side,
Forming the reflective layer on the substrate;
Forming the absorbing layer containing Sn on the reflective layer;
Forming a prevention layer on the absorption layer to prevent oxidation of the absorption layer;
Method for producing a reflective mask blank comprising a. 15. The method of manufacturing a reflective mask blank according to claim 14, wherein the step of forming the absorbing layer and the step of forming the prevention layer are continuously performed in a film formation chamber by using a binary sputtering method.

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